The Organic Light Emitting Display (OLED) possesses many outstanding properties of self-illumination, low driving voltage, high luminescence efficiency, short response time, high clarity and contrast, near 180° view angle, wide range of working temperature, applicability of flexible display and large scale full color display. The OLED is considered as the most potential display device.
The OLED can be categorized into two major types according to the driving methods, which are the Passive Matrix OLED (PMOLED) and the Active Matrix OLED (AMOLED), i.e. two types of the direct addressing and the Thin Film Transistor (TFT) matrix addressing. The AMOLED comprises pixels arranged in array and belongs to active display type, which has high lighting efficiency and is generally utilized for the large scale display devices of high resolution.
OLED display technologies, which is different from LCD display technologies, apply very thin organic material coating and glass substrate, and then these organic materials illuminate without backlight while current pass. However, due to organic material's easy reaction with water and oxygen, as being display equipment of organic material, the criteria of encapsulating of OLED display is very high. In order to cast commercial of OLED display, relative encapsulating technologies become research spotlight.
Currently, the encapsulating of the OLED device is using the encapsulating glue to encapsulate the solid substrate (such as glass or metal), but this method is not suitable for flexible device. Therefore, there is technical solution that using the stack films to encapsulate the OLED device, the method is generally forming two inorganic barrier layers with the capability of preventing penetration of water and oxygen on the OLED device, and forming an organic buffer layer with the flexibility between the two inorganic barrier layers. The inorganic barrier layer is used for preventing penetration of water and oxygen outside the OLED device, and the organic buffer layer is used for releasing the interlayer stress, so the encapsulation structure could apply on the flexible device. However, the organic buffer layer is not compact enough to prevent penetration of water and oxygen, so the capability of preventing penetration of water and oxygen of the encapsulation structure is restricted.
Indium and the alloy of indium are new material in recent years and have some unique properties such as low permeability of water and oxygen, low melting point, good plasticity, and good flexibility, so indium and the alloy of indium have wild application in electronic industry. Wherein, the binary eutectic alloy (low melting point eutectic alloy) consisted of indium and gallium has a compact degree similar to the solid metal, so the capability of preventing penetration of water and oxygen is good and the state at room temperature is liquid. When the binary eutectic alloy consisted of indium and gallium is exposed in the air, the surface will react with the oxygen in the air to form an oxide film. The oxide film is very compact and has good capability of preventing penetration of water and oxygen, so the inside of the material could be prevented from oxidation in order to keep the liquid state and the flexibility.